Orthopedic joint systems may be designed, in particular, in the form of so-called lockable knee joints, which can usually be locked in the maximally extended position, in order to ensure that the patient enjoys a high level of stability while standing. Lockable knee joints are used usually for low-mobility patients for whom the focus is to ensure maximum stance stability and to allow a sitting-down action and sitting with a leg bent. For sitting down, the locking means is released, and therefore the patient can sit down with his foot placed on the floor. The sitting-down movement can be braked via a straightforward damper device. A prosthetic knee joint with a locking means and a hydraulic damping means for sitting down is described, for example, in DE 103 51 916 A1.
U.S. Pat. No. 4,685,926 A relates to a prosthetic knee joint having a mechanical lock which can be overridden via a cable pull. A lever mounted in an articulated manner is connected directly to a cable pull and is pivoted when the cable pull is actuated, this resulting in a locking pin moving out of a recess.
DE 28 48 305 A1 relates to a prosthesis joint for the rotatable connection of two prosthesis parts, having a latching body which is mounted in a rotatable manner on one prosthesis part, is fixed to the other prosthesis part and, over its circumference, has latching gaps, into which can be pushed the nose of a locking means which can be guided against the latching body by the pressure of a spring. The locking means serves for locking the joint and latches into the latching gaps. In order to release the joint, the locking means is pulled out, counter to the pressure of the spring, via a cable pull. The locking means, when the nose of the latter is located within the latching gaps of the latching body, can be fixed via an arresting part which can be pushed in between the locking means and the latching body.
DE 10 2012 009 653 A1 relates to a prosthesis joint having an upper part, a lower part and a locking element, wherein the upper part and the lower part are mounted in a pivotable manner on one another. The locking element can be transferred from a release position into a locked position, wherein, in the locked position, the prosthesis joint can be fixed in a predeterminable flexed state and is braced between the upper part and the lower part. A locking lever can transfer the locking element from the locked position into the release position. The locking element is mounted in the upper part, wherein the upper part has an aperture in which the locking element is mounted in a displaceable manner.
DE 20 2008 002 764 U1 relates to an unlocking mechanism for locked knee joints in the fields of orthopedics, in the case of which finger pressure applied to a push rod moves a lever from its starting position into an end position. This results in deflection of movements by 90° and a transmission of ratio 1:2, in which case a horizontal push-rod movement results in the lever moving vertically by double the distance. Actuation gives rise to unlocking counter to a spring in the knee joint, said spring providing for a restoring force into the starting position. The unlocking mechanism is incorporated by molding.